You should be in the Network Forum but anyway! Bit more information required. Make & Model of Wireless Router? Describe the physical layout between the router and your laptop. (Distance, walls & floors) Are there other wireless networks within range?
The last paragraph is worth forgetting IMHO.
Wireless networks will suffer from interference from other devices, not only other routers transmitting on the same channel (frequency) but microwaves and some DECT telephones. If you sit within a couple of metres of the router what happens to the signal strength?